Analysis of host-pathogen modulators of autophagy during Mycobacterium Tuberculosis infection and therapeutic repercussions

ABSTRACT

Mycobacterium tuberculosis is one of the most deadly human pathogens known today in modern world, responsible for about 1.5 million deaths annually. Development of TB disease occurs only in 1 out of 10 individuals exposed to the pathogen which indicates that the competent host defense mechanisms exist in majority of the hosts to control the infection. In the last decade, autophagy has emerged as a key host immune defense mechanism against intracellular M. tuberculosis infection. Autophagy has been demonstrated not only as an effective antimicrobial mechanism for the clearance of M. tuberculosis, but the process has also been suggested to prevent excessive inflammation to avoid the adverse effects of infection on host. Nevertheless, increasing evidences also show that in order to enhance its intracellular survival, M. tuberculosis has also evolved multiple strategies to compromise the optimal functioning of host autophagic machinery. This review describes an overview of the various host signaling pathways such as pattern recognition receptors, cytokines, nutrient starvation and other cellular stress that have been implicated in induction of autophagy during M. tuberculosis infection. The review also chalk out the complex interplay of several bacterial factors of M. tuberculosis that are known to be involved in compromising autophagy mediated defense of the host. A comprehensive understanding of the interaction of bacterial and host factors at the intersections of autophagic pathways could provide integrative insights for the development of autophagy-based prophylactics and novel therapeutic interventions for TB.

KEYWORDS:

• Autophagy
• endosomal trafficking
• mycobacterium tuberculosis
• phagosome maturation
• pattern recognition receptors
• TB immunotherapeutics

Acknowledgements

Dr. Arshad Khan designed and wrote the manuscript and Dr. Chinnaswamy Jagannath reviewed and edited the manuscript. We thank Dr. Robert L Hunter, Distinguished Professor, McGovern Medical School, University of Texas Health Science Center-Houston for comments that greatly helped in compilation of the manuscript.

Conflict of Interest

The authors have no conflict of interests to disclose.